<mrow><mfenced open="(" close=")"><mrow><mtable><mtr><mtd><msub><mi>a</mi><mi>11</mi></msub></mtd><mtd><msub><mi>a</mi><mi>12</mi></msub></mtd></mtr><mtr><mtd><msub><mi>a</mi><mi>21</mi></msub></mtd><mtd><msub><mi>a</mi><mi>22</mi></msub></mtd></mtr></mtable></mrow></mfenced><mfenced open="(" close=")"><mrow><mtable><mtr><mtd><msub><mi>b</mi><mi>1</mi></msub></mtd></mtr><mtr><mtd><msub><mi>b</mi><mi>2</mi></msub></mtd></mtr></mtable></mrow></mfenced></mrow>
